Ordnance Survey Benchmark in brick

The term benchmark, bench mark, or survey benchmark originates from the chiseled horizontal marks that surveyors made in stone structures, into which an angle-iron could be placed to form a "bench" for a leveling rod, thus ensuring that a leveling rod could be accurately repositioned in the same place in the future. These marks were usually indicated with a chiseled arrow below the horizontal line. Captured using 14 pictures from a Samsung S9 and processed in Agisoft Metashape in June 2021. Source: Objaverse 1.0 / Sketchfab